Defense Secretary James Mattis explains what war with North Korea would look like

Asked by Rep. Tim Ryan of the House Appropriations Committee to explain why the US doesn't just go to war to stop North Korea from developing the capability to hit the US, Secretary of Defense James Mattis painted a grim scenario.

"I would suggest that we will win," said Mattis of a possible war with North Korea. "It will be a war more serious in terms of human suffering than anything we've seen since 1953. It will involve the massive shelling of an ally's capital, which is one of the most densely packed cities on earth," Mattis said of Seoul, which boasts a metro area population of 25 million.

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The scene of the intermediate-range ballistic missile Pukguksong-2's launch test in this undated photo released by North Korea's Korean Central News Agency (KCNA) May 22, 2017. KCNA/via REUTERS ATTENTION EDITORS - THIS IMAGE WAS PROVIDED BY A THIRD PARTY. EDITORIAL USE ONLY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THIS IMAGE. NO THIRD PARTY SALES. SOUTH KOREA OUT.

The long-range strategic ballistic rocket Hwasong-12 (Mars-12) is launched during a test in this undated photo released by North Korea's Korean Central News Agency (KCNA) on May 15, 2017. KCNA via REUTERS REUTERS ATTENTION EDITORS - THIS IMAGE WAS PROVIDED BY A THIRD PARTY. EDITORIAL USE ONLY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THIS IMAGE. NO THIRD PARTY SALES. SOUTH KOREA OUT.

Missiles are driven past the stand with North Korean leader Kim Jong Un and other high ranking officials during a military parade marking the 105th birth anniversary of North Korea's founding father, Kim Il Sung, in Pyongyang, April 15, 2017. REUTERS/Sue-Lin Wong

North Korean leader Kim Jong Un inspects the long-range strategic ballistic rocket Hwasong-12 (Mars-12) in this undated photo released by North Korea's Korean Central News Agency (KCNA) on May 15, 2017. KCNA via REUTERS REUTERS ATTENTION EDITORS - THIS IMAGE WAS PROVIDED BY A THIRD PARTY. EDITORIAL USE ONLY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THIS IMAGE. NO THIRD PARTY SALES. SOUTH KOREA OUT. TPX IMAGES OF THE DAY

People cheer as a missile is driven past the stand with North Korean leader Kim Jong Un and other high ranking officials during a military parade marking the 105th birth anniversary of country's founding father Kim Il Sung, in Pyongyang April 15, 2017. REUTERS/Damir Sagolj

Military vehicles carry missiles with characters reading 'Pukkuksong' during a military parade marking the 105th birth anniversary of country's founding father, Kim Il Sung in Pyongyang, April 15, 2017. REUTERS/Damir Sagolj TPX IMAGES OF THE DAY

North Korean leader Kim Jong Un supervised a ballistic rocket launching drill of Hwasong artillery units of the Strategic Force of the KPA on the spot in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang March 7, 2017. KCNA/via REUTERSATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THE AUTHENTICITY, CONTENT, LOCATION OR DATE OF THIS IMAGE. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. NO THIRD PARTY SALES. NOT FOR USE BY REUTERS THIRD PARTY DISTRIBUTORS. SOUTH KOREA OUT. NO COMMERCIAL OR EDITORIAL SALES IN SOUTH KOREA. TPX IMAGES OF THE DAY

A fire drill of ballistic rockets by Hwasong artillery units of the KPA Strategic Force is pictured in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang September 6, 2016. KCNA/via Reuters ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THE AUTHENTICITY, CONTENT, LOCATION OR DATE OF THIS IMAGE. FOR EDITORIAL USE ONLY. NO THIRD PARTY SALES. SOUTH KOREA OUT. THIS PICTURE IS DISTRIBUTED EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS.

FILE PHOTO - An underwater test-firing of a strategic submarine ballistic missile is seen in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang on April 24, 2016. KCNA/File Photo via REUTERS. ATTENTION EDITORS - THIS IMAGE WAS PROVIDED BY A THIRD PARTY. EDITORIAL USE ONLY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THIS IMAGE. SOUTH KOREA OUT.

A view of a firing contest among multiple launch rocket system (MLRS) batteries selected from large combined units of the KPA, in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang on December 21, 2016. KCNA/via Reuters ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THE AUTHENTICITY, CONTENT, LOCATION OR DATE OF THIS IMAGE. FOR EDITORIAL USE ONLY. NO THIRD PARTY SALES. SOUTH KOREA OUT. THIS PICTURE IS DISTRIBUTED EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS.

Ballistic rocket is seen launching during a drill by the Hwasong artillery units of the KPA Strategic Force in this undated picture provided by KCNA in Pyongyang on July 21, 2016. KCNA/via ReutersATTENTION EDITORS - THIS IMAGE WAS PROVIDED BY A THIRD PARTY. EDITORIAL USE ONLY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THIS IMAGE. SOUTH KOREA OUT. NO THIRD PARTY SALES. NOT FOR USE BY REUTERS THIRD PARTY DISTRIBUTORS.Ã TPX IMAGES OF THE DAY

A test launch of ground-to-ground medium long-range ballistic rocket Hwasong-10 in this undated photo released by North Korea's Korean Central News Agency (KCNA) on June 23, 2016. REUTERS/KCNA ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THE AUTHENTICITY, CONTENT, LOCATION OR DATE OF THIS IMAGE. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. NO THIRD PARTY SALES. NOT FOR USE BY REUTERS THIRD PARTY DISTRIBUTORS. SOUTH KOREA OUT. NO COMMERCIAL OR EDITORIAL SALES IN SOUTH KOREA. THIS PICTURE IS DISTRIBUTED EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS. TPX IMAGES OF THE DAY

A new multiple launch rocket system is test fired in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang March 4, 2016. REUTERS/KCNA ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THE AUTHENTICITY, CONTENT, LOCATION OR DATE OF THIS IMAGE. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. THIS PICTURE IS DISTRIBUTED EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS. NO THIRD PARTY SALES. SOUTH KOREA OUT. NO COMMERCIAL OR EDITORIAL SALES IN SOUTH KOREA

A rocket is launched during a demonstration of a new large-caliber multiple rocket launching system attended by North Korean leader Kim Jong Un (not pictured) at an unknown location, in this undated file photo released by North Korea's Korean Central News Agency (KCNA) on March 22, 2016. REUTERS/KCNA/Files ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THE AUTHENTICITY, CONTENT, LOCATION OR DATE OF THIS IMAGE. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. NO THIRD PARTY SALES. SOUTH KOREA OUT. NO COMMERCIAL OR EDITORIAL SALES IN SOUTH KOREA. THIS PICTURE IS DISTRIBUTED EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS. TPX IMAGES OF THE DAY

A rocket is fired during a drill by anti-aircraft units of the Korean People's Army (KPA) in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang November 3, 2015. REUTERS/KCNA ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THE AUTHENTICITY, CONTENT, LOCATION OR DATE OF THIS IMAGE. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. THIS PICTURE IS DISTRIBUTED EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS. NO THIRD PARTY SALES. SOUTH KOREA OUT. NO COMMERCIAL OR EDITORIAL SALES IN SOUTH KOREA.

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"It would be a war that fundamentally we don't want," said Mattis, but "we would win at great cost."

Mattis explained that because the threat from North Korea looms so large, and a military confrontation would destroy so much, he, President Donald Trump, and Secretary of State Rex Tillerson have all made a peaceful solution a top priority.

China argues it has limited influence with Pyongyang, but as one expert explained, Beijing could cripple the North Korean nation through trade means at any moment, forcing them to come to the negotiating table.

Stratfor

Mattis made it clear that the US was nearing the end of its rope in dealing with North Korea, saying "we're exhausting all possible diplomatic efforts in this regard."

North Korea recently taunted Trump that they were capable of hitting New York with a nuclear missile, but Mattis made it clear that a war today would mostly hurt our Asian allies.

"It would be a serious, a catastrophic war, especially for innocent people in some of our allied countries, to include Japan most likely," said Mattis.